Applications of grips, fittings and grip fitting assemblies for tube and hose line connections and kits within industrial and commercial environments require resistance to harsh environments and reliability under stress and strain forces during installation and operation. Such tube and hose lines may involve high pressure hydraulics or air and often require some flexibility of the tube or hose.
For example, air hose connections are commonly found in applications within the freight hauling industry. Such connections use a device known as a gladhand or gladhand coupler. This is an interlocking hose coupling fitted to hoses supplying pressurized air for air brake operation between a tractor cab unit and a freight trailer, or from a locomotive to railway air brakes on railroad cars. Gladhand couplers resemble a pair of “hands shaking” when interlocked and from where their name is derived. Gladhands are designed to allow the driver to manually disconnect hoses between tractor/trailer or between railcars without a mechanic or tools. They sometimes are quick release to speed up brake release time. Often, gladhands are color coded with service lines being blue and emergency brake lines being red. Mated rubber grommets provide a positive seal, and the joined halves may separate during operation if certain pull stresses are present at the hose or tube connection. Gladhand couplers are typically standardized in size and mating geometry which allows them to be connected to each other, for example allowing either end of a railcar to be connected to the end of a train or for one trucking company's tractor cabs to connect to any number of freight trailers.
Inherent to the freight industry is the constant coupling and decoupling of gladhand connections as trailers are left for loading or unloading and other trailers are picked up for delivery. Gladhands are of course affixed to a length of air hose or tube. The manual act of coupling and decoupling gladhands places stress and strain upon the connected hose. This is exacerbated by the fact that gladhands are prone to corrosion making their mating surfaces more difficult to couple and uncouple over time. During installation and operation of an air brake hose in the freight hauling context, the flexible hose undergoes stress from bending, twisting, and kinking, particularly at the fitting ends of the air brake lines. For instance, tractor-trailer operators subject air brake lines to twisting while bending them into position in tight quarters between tractor and trailer. Drivers and fleet maintenance personnel repetitively connect and disconnect air brake lines between the tractor and trailer using hand holds on the hose at the fittings to achieve the needed leverage to secure and release gladhand connections. Connection of tractor to trailer using integrated, multiple hose and tube and cable assemblies, or “kits,” requires flexibility in the manner of coupling the multiple fittings to their respective fixed air and hydraulic connections.
Conventional grips, fittings and grip fitting assemblies, however, do not offer sufficient protection against kinking of the hose and tube at the gladhand connections. Conventional hose and tube assemblies using only coiled springs at the fittings are subject to corrosion, and provide inadequate protection from the shearing action that takes place during gladhand connection where the spring coils shift and do not prevent kinking and bending during installation and operation. Some rigid grip aids to the gladhand connection process create a more severe angle during tight radius turns putting further stress on air brake lines at the gladhands, reducing the life of air brake hoses and risking failure under operation of the tractor-trailer air brake system.
When not in use (e.g., tractor cab not connected to a tractor trailer), air hoses are often stored in a manner such that the weight of the dangling gladhand stresses the hose to which the gladhand is connected. Further, gladhand connections to the hose, which often include grips, fittings and grip fitting assemblies, undergo continuous exposure to the elements while in use, often in frigid conditions. Winter road salts and brine, dirt, grease, and other solvents erode fittings and assemblies of critical air brake connections. For tractor-trailer connections, protection of fittings that join the air hose and gladhand from the elements with weather resistant, low-temperature materials and coatings is essential to the safety of the driver and public highway motorists.
What is needed is a coupling mechanism that overcomes these and other disadvantages of conventional fittings and fitting assemblies.